1. Field of the Invention
The invention is related to a method of semiconductor fabrication, and more particularly, to a patterning method.
2. Description of Related Art
With the decrease in critical dimension (CD) of the semiconductor device, the demand for the resolution of the lithography process is rising as a result. Since the resolution of the current machine is insufficient, double patterning or multiple patterning is needed to fabricate a smaller CD. However, multiple exposures are needed for the patterning methods, presenting great challenge to pattern placement and overlay. Therefore, how to fabricate a smaller CD has become a relatively important issue in the industry.